Web frameworks do, but the web platform, i.e. browsers don't. The basic abstraction of browsers is still the DOM, which follows the same basic idea of desktop U

Web frameworks do, but the web platform, i.e. browsers don't. The basic abstraction of browsers is still the DOM, which follows the same basic idea of desktop UI toolkits: A tree of elements which you can modify imperatively, combined with event handlers. Only, it's far less sophisticated than the data models of UI toolkits and still optimized for the web's original use case, which were text documents. A lot of the bloat and complexity of web frameworks comes from the issue that they basically have to implement a modern, functional UI toolkit on top of an ancient, imperative one.